Here's a pair of glasses from PixelOptics that replace bifocals, changing from distant vision to close-up with the flick of a switch. Sure, this prototype is rather odd-looking, but its developers say future versions will be indistinguishable from conventional eyeglasses. The technology works using an extremely thin layer of liquid crystal sandwiched between two pieces of glass. Nasser Peyghambarian, a professor of optical sciences at Arizona State University, helped develop the "dynamic" glasses, and had this to say:

"Bifocals effectively work the same way they have since they were invented by Benjamin Franklin. But as any of more than 40 million people in America who need bifocals know, they're a pain."

PixelOptics says it plans to begin shipping glasses using this technology within two years. The first commercially-available smart lenses will be able to switch between near and far vision, but the company is also developing an autofocusing version.